DevTools: cleanup occurences of selection.getRangeAt to avoid NPE

third_party/WebKit/Source/devtools/front_end/platform/DOMExtension.js

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 283 matching lines @@
 }
 
 
 /**
  * @return {boolean}
  */
 Node.prototype.isComponentSelectionCollapsed = function()
 {
     // FIXME: crbug.com/447523, use selection.isCollapsed when it is fixed for shadow dom.
     var selection = this.getComponentSelection();
-    return selection && selection.rangeCount ? selection.getRangeAt(0).collapsed : true;
+    var range = selection && selection.rangeCount ? selection.getRangeAt(0) : null;
+    return range ? range.collapsed : true;
 }
 
 /**
  * @return {!Selection}
  */
 Node.prototype.getDeepSelection = function()
 {
     var activeElement = this.ownerDocument.activeElement;
     var shadowRoot = null;
     while (activeElement && activeElement.shadowRoot) {
@@ skipping 670 matching lines @@
     {
         window.removeEventListener("DOMContentLoaded", windowLoaded, false);
         callback();
     }
 
     if (document.readyState === "complete" || document.readyState === "interactive")
         callback();
     else
         window.addEventListener("DOMContentLoaded", windowLoaded, false);
 }